The present invention relates to pumps and in particular to standing wave pumps.
Pumps are used in many applications to move or compress a pumped fluid (i.e. a liquid or gas). Pumps are typically categorized as dynamic pumps or displacement pumps. Dynamic pumps add energy to a pumped fluid to increase its velocity. Displacement pumps use a volume change to displace pumped fluid in order to compress and pump the fluid. In any event, the majority of conventional pumps use moving parts. Use of moving parts lowers pump efficiency through energy losses against frictional forces. Moving parts also reduce overall pump dependability and increase cost of operation since they are subject to mechanical failure and fatigue and require maintenance. Moving parts also generally require the application of a lubricant, which needs to be replenished and which must be isolated from the pumped fluid.
In order to overcome some of the problems of conventional mechanical moving parts pumps, pumps that have fewer or no moving parts have been proposed. These pumps often pump fluids without using direct mechanical interactions with the fluid to displace or compress the fluid. With fewer moving parts, these pumps are also typically lighter than moving pumps capable of pumping fluids at the same rates and pressures. Such example pumps pressurize fluids using heat, or excite the fluids by various methods. Some pumps achieve a pumping action using the properties of standing waves, and are sometimes referred to as xe2x80x9cStanding Wave Pumpsxe2x80x9d.
In general, these standing wave pumps include a chamber defining a pump cavity. The chamber has a fluid inlet and outlet through which the pumped fluid enters and exits. An excitation source provides excitation energy to establish a standing wave in the pumped fluid in the chamber. The excitation source is matched to the pumped fluid and the length of the excitation chamber so that a travelling wave generated by the excitation source is reflected upon itself within the chamber to create the standing wave. The excitation source may be mechanical, electrical, thermal, electromagnetic or the like. The standing wave results in one or more pressure nodes and pressure anti-nodes within the chamber and the pumped fluid. Generally, the pressure at a pressure node is relatively constant at approximately the undisturbed pressure of the pumped fluid while the pressure at a pressure anti-node fluctuates above and below the undisturbed pressure of the pumped fluid. The inlet and outlet may be placed proximate the pressure nodes and anti-nodes of the chamber, respectively. Thus, fluid may be guided from the outlet through a check valve that prevents the pumped fluid from re-entering the chamber during low pressure portions of the cycle at the pressure anti-node.
In conventional standing wave pumps, the excitation source acts directly on the pumped fluid, and is matched to the speed of a travelling wave within the pumped fluid and the length of the excitation chamber. As such, a particular pump may only be suitable for pumping a single type of fluid. Even more disadvantageously, particular excitation sources may not be effective or may only be able to act on a limited class of pumped fluids. For example, electric and magnetic excitation sources may only act on fluids having certain electric and magnetic properties. Moreover, microscopically, the action of the excitation source may be harsh and could have an adverse effect on the pumped fluid.
There is therefore a need for an improved pump that uses the properties of standing waves.
It is therefore an object of this invention to provide a pump that uses a standing wave within an excitable medium in order to pump fluids.
In accordance with the invention, a standing wave is established within a contained excitable medium. The excitable medium is allowed to exert pressure on a pumping cavity isolated from the excitable medium by a wall. The standing wave acts through the wall to exert pressure on a pumped fluid within the pumping cavity, thereby pumping the fluid through a pumping cavity from an inlet to an outlet.
In accordance with an aspect of the present invention a pump includes an outer body defining a pumping cavity. The outer body includes an inlet and an outlet in communication with the pumping cavity. A housing defines a driving cavity. The housing includes an outer surface at least partially contained within the pumping cavity. An excitable medium is contained in the driving cavity. An excitation source is in communication with the excitable medium to create a standing wave within the excitable medium which causes deformation of the outer surface of the housing. A pumped fluid is pumped from the inlet to the outlet through the pumping cavity by the deformation of the outer surface of the housing when the excitation source is operated.
In accordance with another aspect of the present invention there is provided a pump including a hollow cylindrical housing forming a driving cavity. A hollow cylindrical outer body has a larger diameter than, and is positioned co-axially with the housing forming a pumping cavity therebetween. An excitable medium is provided within the driving cavity. An excitation source creates a standing pressure wave in the excitable medium. The standing wave forms pressure nodes and pressure anti-nodes in the excitable medium. An inlet in the outer body is adjacent to the pressure node of the standing wave. An outlet in the outer body adjacent to the pressure anti-node of the standing wave. A pumped fluid is pumped from the inlet to the outlet through the pumping cavity when the excitation source is operated.
In accordance with yet another aspect of the present invention there is provided a method of pumping a pumped fluid including exciting an excitable medium provided in a housing to produce a standing wave therein and thereby produce deformations in the housing and providing the pumped fluid to a pumping cavity in communication with the housing such that the deformation generates volume changes in the pumping cavity. The pumped fluid is thus pumped through the pumping cavity.
In accordance with yet a further aspect of the present invention there is provided a pump including a housing defining a driving cavity containing an excitable medium. An outer body defines a pumping cavity. The pumping cavity at least partially contains an outer wall of the housing. An inlet and an outlet are in communication with the pumping cavity to guide a pumped fluid to and from the pumping cavity. An excitation source is in communication with the excitable medium, and operable to produce a travelling mechanical wave within the excitable medium. The excitation source, the excitable medium and the driving cavity are matched to produce a standing pressure wave within the excitable medium as a result of the travelling mechanical wave. The outer wall of the housing deforms as a result of the standing pressure wave, and thereby exerts pressure on the pumped fluid within the pumping cavity. The pressure on the pumped fluid forces the pumped fluid from the pumping cavity through the outlet.
In accordance with an aspect of the present invention there is provided a method of pumping a pumped fluid including establishing a standing wave within a secondary fluid; allowing the secondary fluid to exert pressure on a wall in contact with the pumped fluid, to deform the wall; using deformation of the wall to pump the pumped fluid from an inlet to an outlet.
In accordance with an aspect of the present invention there is provided a pump including an outer body and a wall within the outer body. The outer body and the wall define a pumping cavity and an excitation cavity within the outer body. An excitable medium is within the excitation cavity. A pumped fluid is within the pumping cavity. An excitation source is coupled to the excitable medium. The excitation source is operable to excite the excitable medium and create a standing wave therein. The standing wave acts through the wall to pump the fluid through the pumping cavity.
Other aspects and features of the present invention will become apparent to those of ordinary skill in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.